Tailoring the SnO2 electron transport layer with hydrofluoric acid to assemble efficient and stable HTL-free perovskite solar cells

Perovskite solar cells (PSCs) without any hole transport layer (HTL) offer cost-effective photovoltaics for the world's energy demands. The current study focuses on improving the photovoltaic performance and stability of this kind of PSC by employing an interface modification of the tin(iv) oxide (SnO2) electron transport layer (ETL). For this mission, hydrofluoric acid (HF) with different concentrations was used as a modifier and spin-coated over the SnO2 ETL. Results showed that HF-based treatment increases charge transfer at the ETL/perovskite interface by reducing charge traps in the interface, leading to a champion efficiency of 14.65% for treated PSCs, higher than the 12.92% recorded for the control PSCs. In addition, HF modification improves the wettability of SnO2 for perovskite precursors and forms a smoother and more compact perovskite layer, which boosts stability behavior in treated PSCs.